To do the design for space frame structure , we must first have a deep understanding of the engineering situation of the structure.There are many factors that should be considered in the project overview, generally including engineering geological conditions, structure span, substructure of space frame structure, climatic conditions, etc. These factors are usually the basis for the selection of the space frame structure.
The structure form selection includes the selection of the type of the space frame structure, the size of grid, the thickness of grid, the position of support and the form of constraint.
After the selection of space frame structure form, the finite element analysis model of the space frame can be established.In general, the space frame structure is built by the rod element in finite element, and the joints are simplified as hinge connections.
At present, the load of the space frame structure can be evaluated according to the Load Code for Building Structures (GB 50009-2012). The design load usually includes static load, live load, wind load, earthquake load and temperature function, and all possible combinations of load conditions should be considered.
The analysis of the mechanical performance for space frame structure includes two parts :static performance and dynamic performance.Firstly, the static performance analysis is carried out to check whether the bars exceeding the allowable stress, namely the strength condition, under the combination of various load conditions.Then check whether the maximum displacement of the structure exceeds the allowable displacement, that is, the stiffness condition.After the above two conditions are satisfied, the dynamic performance analysis shall be carried out. If not, the structural scheme shall be modified.
At present, dynamic performance analysis mainly refers to seismic analysis of space frame structure.The common seismic analysis methods include response spectrum analysis and dynamic time-history analysis. The dynamic stress and displacement of the structure are calculated to verify whether the strength and stiffness conditions can be met.
After the structural design meets the requirements of mechanical properties, the construction methods of the points and supports should be considered at the actual construction time ,so as to make the construction methods as consistent as possible with the theoretical analysis model.Finally, the construction drawing is made.